The use of satellite-based and aerial-based imagery is popular among government and commercial entities. To such entities, it can be useful to piece together thousands of separate images into an orthomosaic image. Unfortunately, because it is not a routine matter to align and orient separate images relative to each other to produce this orthomosaic, misalignment errors are common. Misalignment errors can result in a straight road or edge of a building appearing in the orthomosaic as a road or building edge with a inflection point at the seam between images or in which the road segments in the two different images on either side of the seam do not intersect (see misaligned roads, parking lots, and buildings in FIG. 1).
In order to produce a quality orthomosaic image, a ground control network of a plurality of ground control points (GCPs) can be used. When one or more GCPs can be found in adjacent images, the GCPs can be used to orient the adjacent images so that they are properly aligned. When this is done satisfactorily, it will not be readily apparent that the combined image is a combination of more than one image.
A technique for creating a ground control network is disclosed in Dolloff, J., and M. Iiyama (2007), “Fusion of Image Block Adjustments for the Generation of a Ground Control Network,” Proceedings from the Information Fusion, 2007 10th International Conference, Jul. 9-12, 2007 and U.S. Pat. No. 8,260,085 (collectively, “Dolloff”), the entire contents of each of which are incorporated herein by reference. This technique includes creating a ground control network of multiple ground control points (GCPs) from overlapping images generated from aerial and space-borne sensors and measurements of ground points in those images. The process of selecting the GCPs is performed manually and can be labor intensive. In addition, the processing is performed in a serial fashion in Dolloff, which is computationally intensive.